Storage tanks for holding a variety of fluids are known. Often these storage tanks are used to store environmentally hazardous fluids such as fuel oil or gasoline. These storage tanks are often equipped with venting systems to allow for air flow out of the tank during filling operations or to allow for air flow into the tank during fuel consumption in order to maintain air pressure balance between the air pressure in and out of the tank. These venting systems often consist of a simple opening on the top of the storage tank, which may connect to a vent pipe that extends to the outside atmosphere when the storage tank is located within an enclosed structure. During the filling operations and when an overfill of the tank occurs, the fluid will be forced through the venting system and outside the tank, thus creating an environmental hazardous spill condition.
Storage tanks for storing environmentally hazardous fluids are often equipped with fill alarms that alert pump truck operators when a fluid level in a tank reaches an upper limit during the filling operation. One type of fill alarm is a whistle fill alarm that produces a whistling sound during the fill operation by allowing air to be forced through an orifice in the fill alarm. When the fluid enters into the whistle, the whistling stops, alerting the operator to cease the filling operation. As in systems without fill alarms, the filling process often continues passed the upper limit of the tank and a spillage of the environmentally hazardous fluid can occur through the orifice in the whistle fill alarm.
The present invention solves at least these problems occurring in the prior art.